1. Field of the Invention
The present invention relates to a process for preparing a catalyst used in producing methacrylic acid by the gas-phase catalytic oxidation of methacrolein.
2. Description of the Prior Art
Hitherto, a large number of proposals have been made in regard to a process for producing methacrylic acid by the gas-phase catalytic oxidation of methacrolein and a catalyst used therefor. For example, with the object of controlling micropores in the catalyst, it is proposed to use alcohols, nitrogen-containing heterocyclic compounds and other various compounds at the time of preparation of the catalyst (see for example Japanese Patent Application Kokai No. 60-239439 and No. 55-73347). However, these proposals have defects in that the results of reaction are not sufficient, the catalytic activity decreases significantly with the lapse of time and after-treatment is troublesome. At present, therefore, a further improvement in a process for preparing industrially usable catalysts is desired.